I was encouraged to collect things as a kid. I think it was even a badge in cub-scouts. I collected keyrings. I was given them from various places, spent pocket-money on them on holiday, that sort of stuff. I certainly didn't own any keys. I also collected model dinosaurs (usually acquired at museums) and Lego.

The Lego I would put in its own category because it was endlessly fascinating and rebuild-able. I used it all the time. The dinosaurs were at least educational.

But the keyrings were just hoarded and gathered dust. I'm trying to decide now if this was unhealthy and trained me to covet stuff, or if it was a good inoculation against the behaviour later in life. I now have zero interest in collecting anything just for the sake of collecting it. I'd rather be minimal where possible, and after accumulating a lot of crap in my early 20s (when owning stuff was a novelty) I now also try to avoid the "I might use that someday" trap.

I too like fountain pens and have about six, moderately priced, all made by 'Cross'. I put various coloured inks in them (I usually have about 3 good to go at any one moment) and ... I virtually never hand write anything.

The thing I have most of is certainly cables and tech widgets of various descriptions, but I don't try to collect them, somehow they just sort-of happen.

Make of that all what you will.